The TD expects to become the butt of some corny jokes because of the company name – but when he was asked to join the board of the investment firm he had no hesitation in saying yes.

"I've been buying and selling shares for many years and I got to know a group of investors from England – and when they asked me to become a director of the firm I was glad to accept," the Limerick TD explained last week.

The ex-minister, who regards investing in shares as "a hobby", said that becoming a company director last November was a challenge – and he was fitting in his business duties on top of his punishing schedule as a TD and one of the most hard-working constituency representatives in Ireland.

Union Jack Oil, which invests in exploration companies in the final stages of drilling for oil and gas, has no business interests or investments in Ireland.

"So there is no conflict of interest", he is quick to point out.

"Finding oil and gas is an extremely long process and by the time it comes to the drilling stage a company could be four years down the line – and that's when our company gets involved. We have a large fund and at the drilling stage we invest," he says.

Fellow directors David Bramhill, Joseph O'Farrell and Martin Durham all have long experience in the oil and gas industry.

"I am not too interested in the money side, it is more of a challenge," says Mr O'Dea, who has been a poll-topper in Limerick and served as Minister for Defence in Bertie Ahern's government.

His new position as a director of Union Jack Oil will be included in the next 'Declaration of Interest' register compiled for members of Dail Eireann. The qualified barrister also has a portfolio of shares and investments.

Mr O'Dea says: "It was through investing that I got to meet these guys and we hit it off. I was delighted when they asked me to join the board."

Since Mr O'Dea joined the board, the company's shares have begun trading on the ISDX market in London and it is planning to float on a larger AIM market in the future.

Mr O'Dea, who also writes for the Sunday Independent, has investments in a range of exploration companies and, like other investors, he is a "follower" of entrepreneur John Teeling, a long-time promoter of oil, gas and mining firms in Ireland and abroad, as well as the founder of the Cooley Distillery, which was recently sold to the American drinks giant Jim Beam.